1. Field of the Invention
The present invention relates to an image processing system in which plural units for image formation on a recording material, such as copiers or facsimile devices, are controlled in their combination to achieve various image processing operations.
2. Description of the Prior Art
In case of producing a document for example by combining plural original documents, it has conventionally been necessary to overlay sentences or drawings plural times on a recording sheet by means of one or plural copying machines. For this reason, in such conventional apparatus, the operator has to conduct complicated manual copying operations, such as plural actuations of copy button or manual transfer of copying sheets, after a copying operation to the manual insertion slot. Also a multi-color copying has only been achieved by an expensive color copier. Multi-color copying is possible by a similar procedure if plural units of relatively inexpensive monocolor copiers are used with developers of respectively different colors and if the original is separated into different colors, but such process will require extremely cumbersome operations to the operator in the same manner as explained above.
In order to avoid such complicated operation there have been proposed a copier with an editing function, for example a color copier with ordinary three-color overlaying process, in which a control unit overlays the image information of plural originals on a photosensitive drum or in a memory device and then transfers such information at a time onto the recording sheet, or a copier capable of forming a latent image on a photosensitive drum at a time by optically editing plural originals, in which for example a control unit controls plural optical systems to focus plural images onto a photosensitive drum, but such copiers are inevitably large and considerably expensive.
In consideration of such present situation where the price of a copier of advanced function as explained above is almost equal to the sum of prices of plural simple copiers, it will be convenient if the above-described editing or multi-color copying can be achieved by connecting plural units of inexpensive copiers through simple link mechanisms, since such structure will simplify the required copying operation and reduce the cost in comparison with the prior copier with advanced function, and still allow independent use of each copier unit when required.
However, in such structure, an unsatisfactory linkage, for example a curved linkage, may lead to skewed or swaying advancement of the recording sheets, eventually resulting in sheet jamming. Also unmatched timings between the copier units will result in aberration of characters or images on the come or is sheet jamming. Furthermore, such abnormality as sheet jamming may lead to a major trouble unless certain copier units are appropriately stopped.
Furthermore, even in such linked state, a complicated procedure will be required if the operating panels of different copier units have to be manipulted, and such linked structure will be unable to perform normal combined function if each copier unit starts an independent operation by an erroneous manipulation of the operating panel thereof.
Furthermore, in such linked structure of plural copier units, the timing control of sheet feeding with ordinary sheet feeding rollers and registration rollers is difficult in a downstream copier unit receiving the recording sheets from an upstream copier unit, since the recording sheet may still be in the fixing station of the upstream copier unit, and such failed sheet feeding control may result in sheet jamming.
Furthermore, in such linked structure, each copier unit in said structure has to be appropriately stopped for safety in case of an abnormality such as sheet jamming, but such stoppage may result in a significant loss of recording sheets since the recording sheets present in the copier units downstream of the failed copier unit are in normal state.